1. Field of the Invention
This invention relates to a device that can be readily used for de-airing multi-ply laminates of different shapes, thickness, and sizes. Today, multi-ply laminates are widely used in industry and consumer products. For example, automobile windshields and some building windows are made from laminated glass in order to improve safety or security. Unlike ordinary glass, upon impact laminated glass will not shatter but will only break or crack.
2. Related Background Art
Laminated glass is usually made of one or more sheets of thermoplastic material, such as polyvinyl butyral (xe2x80x9cPVBxe2x80x9d), bonded to two sheets of glass, forming a so-called xe2x80x9csandwichxe2x80x9d structure. To be used, for example, as an automobile windshield, the laminated glass must be made optically transparent. Typically, the surfaces of the inner polymer are uneven and when the sheets are pressed together during lamination, air bubbles are trapped in the uneven portions, decreasing the transparency of the final product. In order to eliminate the deleterious air bubbles, an evacuation system must be constructed to xe2x80x9cde-airxe2x80x9d the multi-ply laminate.
In a typical de-airing technique, an assembly is enclosed within a closed ring comprising one or more channel-shaped members of a fluid-impervious material (such as rubber). Various types of de-airing rings are known.
U.S. Pat. No. 1,870,284 to Drake discloses the use of rigid peripheral evacuation chambers to apply suction to two adjacent sides of an assembly of glass and inter-layer sheets to evacuate air from the interfaces between the sheets during lamination. These evacuation chambers had to be aligned exactly with the side faces of the assembly, perfectly matching their thickness because of a lack of flexible lips that engage the outside major surfaces of the assembly.
U.S. Pat. No. 2,948,645 to Keim discloses using a de-airing ring comprising an endless flexible, air-impervious channel-shaped member having flexible lips that fit over the outer edge portions of an assembly of curved glass sheets and a flexible interlayer sheet to be laminated. This patent requires that the evacuation channel extend around the complete periphery of the assembly. Thus, each different outline shape of an assembly to be laminated requires a different shape for the channel shaped member that defines the evacuations chamber.
Other patents that describe enclosing the peripheral edge of an assembly to be laminated within the lips of a de-airing ring comprising a flexible channel member include U.S. Pat. Nos. 3,074,466 and 3,074,838 to Little, U.S. Pat. No. 3,100,173 to Boicey et al., U.S. Pat. No. 3,234,062 to Morris, U.S. Pat. No. 3,249,479 to Boicey, U.S. Pat. No. 3,281,296 to Jameson, U.S. Pat. No. 3,852,136 to Plumat et al. and U.S. Pat. No. 4,624,731 to Ash et al.
In these patents, the flexible channel members extend continuously around the periphery of the assembly to be laminated. This approach suffers from a deficiency in that it necessitates using a different size ring for a different size laminate. Since the ring must surround the periphery of the laminate and then be attached to the vacuum pump, that ring will no longer be sufficient to provide an airtight connection with the glass when the size of the laminate changes. Therefore, it is necessary to maintain an inventory of flexible channel members for each production pattern. The storage and inventory problem is tremendous. Also, the fabrication of such channel members is expensive, requiring a separate mold for each pattern if the channel member is made as a single piece, or from several molds followed by a vulcanizing step, if the channel member is made in several sections.
In addition, it is not believed that the systems described in the above listed patents could be employed for negotiating a sharp corner without a specific, integrated ring corner piece that may or may not be an inherent part of the ring construct. It is further believed that the materials that comprise and/or the shape of the vacuum channels in the prior art are as such that negotiating a sharp corner without a fitted ring corner piece would likely block air flow or eliminate a tight seal between the ring and the glass that would result in a loss of vacuum, thereby negating the purpose for having an evacuation system.
U.S. Pat. No. 2,992,953 (Talburtt) describes a de-airing ring made of flexible channeled tubing, wrapped about most of the periphery of a laminate, and a grooved supporting strip that is attached to the remaining exposed edge of the laminate. The invention covered by this patent represents an improvement over the endless rings of the other patents in that the Talburtt de-airing ring is not limited to a specific size and it, allegedly, is not as difficult or time consuming to apply as the endless rings of the other patents. Instead, the Talburtt de-airing ring is applied by mounting a bottom edge of the assembly into the grooved supporting strip, applying the flexible channel tubing about the remainder of the periphery of the assembly and clamping appropriate portions of the flexible channel tubing to the ends of the grooved supporting strip. A portion of the flexible channel tubing is left beyond each clamped portion. Different lengths of flexible channel tubing remain for different patterns depending on the length of the perimeter of the assembly to be laminated.
The Talburtt invention, however, is limited in its application to automobile windshields that have an edge straight enough to be received within the grooved supporting strip and corners of sufficiently rounded configuration to enable the application of the flexible channel tubing to the periphery of the assembly without having the tubing buckle in the vicinity of any sharp corners. The Talburtt de-airing rings would not likely be suitable for laminating windows of a rectangular or polygonal configuration that has sharp corners, such as those used in buildings.
U.S. Pat. No. 4,398,979 (Cathers et al.) attempts to overcome many of the above described issues that are involved in making large and variably sized windows with sharp corners. This patent describes a laminating method using a plurality of channel-shaped members and connecting channel-shaped connection pieces all attached to the periphery of a laminate. However, Cathers et al. is still plagued by deficiencies. It requires new channel-shaped and connecting members for each laminate of different shape and size. This escalates production costs, increases storage needs and lengthens the time period required to replace the old members in order to conduct another lamination. Even a single laminate requires multiple members in order to carry out the lamination. For example, a rectangular laminate would necessitate four channel-shaped members and four connecting members that have to be specifically fitted for the angles and dimensions of this particular laminate. This approach also significantly increases the potential for air/vacuum leaks because multiple connecting pieces are employed.
The use of laminated glass is widespread. An urgent need exists for a new, cost-effective de-airing device that is easily adjustable to fit laminates of different shapes, sizes and thickness. Particularly, a device is needed to de-air laminates with sharp corners and large architectural window panels. The present invention meets these needs.
This invention is directed to a de-airing ring comprising: a) a flexible vacuum ring having a longitudinal channel imbedded therein that can be matingly mounted about a periphery of a laminate; b) a male connector attached to one end of the flexible vacuum ring; c) at least one vacuum connection port communicating with the longitudinal channel.
The male connector is designed and shaped to slidingly engage the longitudinal channel of the vacuum ring at any location along its length to form an airtight seal while enclosing the ring around the periphery of an assembly of the multiply laminate, and to provide gas flow through the flexible vacuum ring mounted about the periphery of the laminate.
Also provided is a device for de-airing laminates of different shapes, sizes, and thickness where a male connector further comprises a connector channel, fluidly engaging the longitudinal channel at one end of the flexible vacuum ring, to provide gas flow through the flexible vacuum ring mounted about the periphery of the laminate.